Surface nanostructure of a directionally solidified Ni-based superalloy DZ4 induced by high intensity pulsed ion beam irradiation

摘要

A high intensity pulsed ion beam (HIPIB) was used to irradiate directionally solidified nickel-based superalloy DZ4 with the following parameters: ion content consisting of C~(n+) (30at.%) and H~+(70at.%), an accelerating voltage of 250 kV, a pulse duration of 70ns, a beam current density of 100A/cm~2, irradiation times of 15. As revealed by SEM and TEM, the thermal effect was confined in a ～1.3 μm thick surface zone, in which rapid melting and cooling occurred. A two-phase nanostructured layer of ～10 nm thick was formed on the outmost surface. The component phases are the y phase and the carbide with a particle size of ～5-10 nm. The presence of dense dislocation networks was observed in depth in the substrate metal, for instance ～20 μm away from the sample surface, which is caused by shock wave impact.